GH-111435: Add Support for Sharing True and False Between Interpreters (gh-111436)

This only affects users of the APIs in pycore_crossinterp.h (AKA _xxsubinterpretersmodule.c and _xxinterpchannels.c).

Lib/test/test_interpreters.py

@@ -778,6 +778,8 @@ class TestIsShareable(TestBase):
                 'spam',
                 10,
                 -10,
+                True,
+                False,
                 100.0,
                 ]
         for obj in shareables:
@@ -797,8 +799,6 @@ class TestIsShareable(TestBase):
 
         not_shareables = [
                 # singletons
-                True,
-                False,
                 NotImplemented,
                 ...,
                 # builtin types and objects